J Street will not draw as many "disaffected Jews" as it does "disillusioned Zionists". In other words it will not increase the number of Zionists, rather it will provide a step away from Zionism for those who need a compromise. It's one more bungled try at salvaging Israel abroad. There is only one answer to Israel's problems. A Palestinian state that exists in a way that justifies the past problems of its population. Right now Israel's settler led politics make that kind of state less likely to arise alongside Israel. That does not make the Palestinian state less likely, it makes Israel's survival less likely.
Opposition leader Isaac Herzog calls on government to allow Syrian refugees into Israel (Haaretz)
from the article: Israel’s problem is the settlements, not J Street